code: def test_cross_entropy():
      spawn_for_all_world_sizes(run_test_cross_entropy)
  
file_path: fairscale/tests/nn/model_parallel/test_cross_entropy.py
imports: import torch
  import torch.nn.functional
  from fairscale.fair_dev.testing.testing import IdentityLayer, dist_init, set_random_seed, spawn_for_all_world_sizes
  from fairscale.nn.model_parallel import initialize
  from fairscale.nn.model_parallel.cross_entropy import vocab_parallel_cross_entropy
  from fairscale.nn.model_parallel.mappings import scatter_to_model_parallel_region
label_desc: Use image node_id 4 for calling a global function with example usage: test_cross_entropy() without return types